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46 lines
1.2 KiB
C++

#pragma once
#ifdef _WIN32
#include "safewindows.h"
#if defined(WINAPI_FAMILY) && WINAPI_FAMILY != WINAPI_FAMILY_DESKTOP_APP && _WIN32_WINNT >= 0x0A00
// Prefer the *FromApp versions when we're being built in a Windows Store App context on
// Windows >= 10. *FromApp require the application to be manifested for "codeGeneration".
#define VirtualAlloc VirtualAllocFromApp
#define VirtualProtect VirtualProtectFromApp
#endif // App family partition
inline void *allocate_pages(size_t size)
{
return VirtualAlloc(nullptr, size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
}
#else
#include <sys/mman.h>
inline void *allocate_pages(size_t size)
{
void *ret = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
return ret == MAP_FAILED ? nullptr : ret;
}
#endif
template<typename T>
class PoolAllocate
{
static constexpr size_t PageSize = 4096;
static constexpr size_t ChunkSize = sizeof(T) * PageSize;
static inline size_t index = PageSize;
static inline T *buffer = nullptr;
public:
static T *allocate()
{
if (index == PageSize)
{
index = 0;
buffer = static_cast<T*>(allocate_pages(ChunkSize));
}
return &buffer[index++];
}
};